Mobile devices, such as cellular “smart” phones, MPEG-1 Audio Layer III (MP3) devices, Wi-Fi-capable devices, and the 6 like, have become increasingly popular due to their continually enhanced functionality and performance. A popular (and often necessary) feature incorporated into most of these devices is an audio speaker for producing sounds, such as music or the spoken word. In many cases, a connector may also be supplied on the device to allow the user to connect earphones or similar devices for sound reproduction.
A significant concern of mobile device manufacturers is the protection of audio speakers that are incorporated into the device from damage due to improper voltages being placed across the speaker. A common type of damage-inflicting voltage is a direct-current (DC) mode voltage of sufficient magnitude and duration to cause permanent speaker damage. Preventing the application of such a voltage across a speaker is often difficult to implement, as some typical audible low-frequency audio signals may exhibit the characteristics of a voltage signal capable of damaging a speaker.